KR20240064669A - rolling bearing - Google Patents

Abstract

In order to create a rolling bearing with excellent oil film formation ability on the peripheral surface 10 of the raceway rings 1 and 2 and the sliding portion of the guide surface 12 of the retainer 4, the outer ring 1 and the inner ring 1 are The composite roughness of the circumferential surface 10 of one of the orbital rings 2 and the guide surface 12 of the retainer 4 is 0.7 ㎛ or less, and the roundness of the circumferential surface 10 is 30 ㎛ or less, Increase the parameters of the sliding section.

Description

rolling bearing

The present invention relates to a rolling bearing having a raceway guide type retainer.

The method of guiding the retainer in the radial direction can be roughly divided into a method of guiding a retainer in which the rolling elements are evenly arranged in the circumferential direction, a rolling element guiding method by sliding between the inner surface of the pocket of the retainer and the rolling elements, and a method of guiding the retainer by sliding between the inside and outside of the pocket of the retainer. There is a method of guiding the bearing rings by sliding between the circumferential surface of one of the bearing rings and the guide surface of the retainer.

In the case of the orbital ring guidance method, a guidance margin is set between the guide surface of the retainer and the circumferential surface of the orbital ring. If the eccentricity of the cage with respect to the raceway exceeds the range of the guide clearance, the guide surface of the cage slides in the circumferential direction relative to the circumferential surface of the raceway. At this time, the sliding portion of the guide surface of the retainer and the circumferential surface of the bearing ring is lubricated by the oil present inside the rolling bearing.

Patent Document 1: Japanese Patent Publication No. 2016-169766

In a raceway-guided cage, when the composite roughness of the peripheral surface of the ring and the guide surface of the cage is large, an oil film may form on the sliding portion of the peripheral surface of the ring and the guide surface of the cage, especially during low-speed rotation of the rolling bearing. This is difficult to form, and its sliding resistance becomes resistance in the rotation of the rolling bearing.

In addition, when the surface roughness of the circumferential surface of the raceway made of a hard material is large, the aggression against the guide surface of the retainer when the oil film is broken in the above-mentioned sliding portion is strong, leading to early damage to the guide surface.

In addition, between the guide surface of the retainer and the circumferential surface of the raceway, a wedge-shaped gap that gradually narrows in the circumferential direction is formed in the sliding portion on both sides, so a wedge-shaped gap occurs when oil is drawn into the wedge-shaped gap in the circumferential direction. This has the effect of promoting the formation of an oil film in the sliding part, but if the roundness and roughness of the circumferential surface of the raceway are not appropriate, an oil film is not formed in the sliding part, solid contact occurs on both sides, and the sliding resistance further increases. , the risk of early damage increases.

Taking the above-mentioned background into consideration, the problem to be solved by the present invention is to create a rolling bearing with excellent oil film formation ability on the peripheral surface of the bearing ring and the sliding portion of the guide surface of the retainer.

In order to achieve the above object, this invention provides an outer raceway ring having an outer raceway surface, an inner raceway ring having an inner raceway surface, and a device arranged between the outer raceway surface and the inner raceway surface. It is provided with a plurality of rolling elements and a retainer that maintains a circumferential distance between the plurality of rolling elements, and one of the outer and inner bearing rings has a circumferential surface that guides the retainer. , the retainer is a rolling bearing having a plurality of pocket inner surfaces for holding the rolling elements and a guide surface guided on the circumferential surface, wherein the combined roughness of the circumferential surface and the guide surface is 0.7 ㎛ or less, and the circumferential surface A configuration with a roundness of 30 μm or less was adopted.

According to the above configuration, the composite roughness of the guide surface and peripheral surface of the retainer and the peripheral surface of the bearing ring, which greatly affect the sliding resistance and aggressiveness, and the roundness of the peripheral surface of the bearing ring, are set to 0.7 ㎛ or less. Since the roundness of the circumferential surface is small to 30 ㎛ or less, the oil film parameter in the sliding portion on both sides can be increased to obtain excellent oil film forming ability.

This invention has an annular portion and two or more claw portions protruding in one axial direction from the annular portion at an interval in the circumferential direction, and a pocket between the claw portions adjacent to each other in the circumferential direction accommodates the rolling element. It is suitable for retainers made of . Since this type of retainer has a cantilevered claw portion, it is easier to deform due to centrifugal force compared to a basket-type retainer with a pillar portion partitioned between two annular portions, and the high-speed rotation provides guidance between the guide surface of the retainer and the circumferential surface of the raceway ring. It is easy to change with limited margin. As described above, if the composite roughness and the roundness of the circumferential surface are set small, it is possible to prevent oil film breakage or premature damage to the sliding portion even when rotating at high speed.

further comprising a locking member disposed on the other axial direction with respect to the retainer so as to regulate movement of the retainer in the other axial direction, wherein the annular portion has a back surface that faces the locking member in the axial direction, The annular portion and each of the claw portions may be integrally formed by injection molding, and the injection molded gate may be disposed on a portion of the surface of the retainer excluding the guide surface and the back surface. If the movement of the retainer in the other axial direction is regulated by the locking member, the protruding height of the claw portion can be shortened and deformation of the retainer due to centrifugal force can be suppressed. Additionally, if the annular portion and each claw portion are formed integrally by injection molding, the mass production of the retainer is excellent. The position of the gate in the injection molding corresponds to the position of the gate trace on the surface of the retainer, but burrs may occur in the gate trace during release. If the gate is located in an area other than the guide surface and the back of the retainer, even if a burr occurs in the gate trace of the retainer, the retainer can be guided to the orbital ring or the short claw portion of the retainer's back is used as a locking member to move it. When regulating, the burr of the gate trace does not rub against the circumferential surface of the raceway or the locking member, so it does not increase the rotational torque of the rolling bearing or cause noise or vibration.

Considering the protrusion height of the claw portion in one axial direction with respect to the annular portion, the difference in protrusion height between each claw portion may be within 120 μm. Among the plurality of claw parts, a claw part with an excessively protruding height may increase the sliding area with the rolling element, which is undesirable in reducing the rotational torque of the rolling bearing, while a claw part with an excessively protruding height may increase the sliding area with the rolling element. There is a risk that it may not be sufficiently maintained, so it is not desirable. In order to avoid these problems, it is preferable that the difference in protrusion height between each claw portion is small to within 120 μm.

The combined roughness of the inner surface of the pocket of the retainer and the surface of the rolling element held on the inner surface of the pocket may be less than 0.51 μm. Heat generation can be suppressed by alleviating the increase in sliding resistance between the inner surface of the pocket and the surface of the rolling element.

The outer diameter and inner diameter of the retainer may each be within 600 μm. In this way, by reducing the outer diameter drift and inner diameter drift of the cage, shaking during rotation of the cage can be suppressed.

For example, the retainer can be formed of polyamide resin. As described above, if the composite roughness of the guide surface of the retainer and the circumferential surface of the raceway ring and the roundness of the circumferential surface are set small, heat generation due to sliding resistance of these guide surfaces and the peripheral surface or aggression of the peripheral surface against the guide surface can be suppressed. Therefore, even if polyamide resin, which is inferior to super engineering plastic in heat resistance, is used as the retainer material, the retainer can be made capable of withstanding use at high-speed rotation.

It is good if the oil lubricating the retainer has a kinematic viscosity of 50 cst or less at 40°C. If the kinematic viscosity of the oil is high, the agitation resistance of the oil by the retainer or rolling element increases, making it easy for the rolling bearing to rise in temperature, and further impairing energy saving. If the retainer is lubricated with a low-viscosity oil that has a kinematic viscosity of 50 cst or less at 40°C, the agitation resistance of the oil inside the bearing can be suppressed.

The rolling bearing according to this invention is suitable for use in supporting a rotating shaft included in a motor or a transmission connected to the motor. As described above, the rolling bearing according to this invention has excellent lubrication of the sliding portion when guiding the retainer to the bearing ring, and is therefore suitable for high-speed rotation applications such as the rotating shaft of a motor.

Here, the motor refers to at least one of an electric device that converts electrical energy and outputs rotation as a driving source, and an electrical device that converts input rotation into electrical energy. In addition, a transmission refers to a device that converts the input rotation speed and transmits it to the output side. A continuously variable transmission device in which the ratio of the speed conversion (reduction ratio, transmission ratio) changes continuously, and a fixed ratio transmission device in which the ratio of the speed conversion is fixed. It is a concept that includes, and the fixed ratio transmission device includes what is called a reducer or increaser that has only one type of speed conversion ratio.

As described above, in the present invention, by employing the above-described configuration, the oil film parameter on the sliding portion of the circumferential surface of the bearing ring and the guide surface of the retainer can be increased, making it possible to create a rolling bearing with excellent oil film forming ability.

1 is a half-sectional view showing a rolling bearing according to an embodiment of the present invention.
Figure 2 is a partial perspective view showing the rolling bearing according to the embodiment partially cut away.
Figure 3 is a perspective view of a retainer according to the embodiment.
Figure 4 is a cross-sectional view of a retainer according to the embodiment.
Figure 5 is a right side view of the retainer of Figure 4.
Figure 6 is a schematic diagram showing an example of use of a rolling bearing according to the embodiment.

An exemplary embodiment of a rolling bearing according to the present invention will be described based on FIGS. 1 to 5.

The rolling bearing shown in FIGS. 1 and 2 includes an outer bearing ring 1, an inner bearing ring 2 arranged coaxially with respect to the outer bearing ring 1, and these bearing rings 1 and 2. It is provided with a plurality of rolling elements (3) disposed between them and a retainer (4) that maintains the circumferential spacing of these rolling elements (3).

Here, the direction along the central axis in a state where the central axes of the inner and outer bearing rings 1 and 2 and the retainer 4 coincide is referred to as the “axial direction.” Additionally, the direction along the circumference around the central axis is referred to as the “circumferential direction.” Additionally, the direction perpendicular to the central axis is referred to as the “radial direction.” Additionally, the inner diameter or outer diameter refers to the diameter of a virtual inscribed circle or virtual circumscribed circle concentric with the central axis. Additionally, the side radially away from the central axis is called the radially outer side, and the side radially closer to the central axis is called the radially inner side. In Fig. 1, the central axes of the inner and outer orbital rings 1 and 2 and the retainer 4 coincide, and the left and right directions in Fig. 1 correspond to the axial direction, with one axial direction being the right, and opposite to this. The other axial end of is to the left. Additionally, in Fig. 1, the radial direction corresponds to the vertical direction.

The outer raceway ring 1 is an annular bearing part with an inner circumference including an outer raceway surface 5. The inner raceway ring 2 is an annular bearing part with an outer circumference including the inner raceway surface 6.

The rolling element 3 includes balls. The plurality of rolling elements (3) are interposed between the outer raceway surface (5) and the inner raceway surface (6). Each raceway surface 5, 6 includes a raceway groove having an arc-shaped cross section. In the city, a deep groove ball bearing is illustrated.

The retainer 4 is an annular bearing part that holds the plurality of rotating bodies 3 so that they are evenly arranged in the circumferential direction. The retainer 4 holds the plurality of rolling elements 3 so that they are evenly arranged in the circumferential direction.

One of the outer bearing ring 1 and the inner bearing ring 2 is fixed to rotate integrally with a rotation axis (not shown), and the other is fixed to a housing (not shown) that is stationary with respect to the rotation axis.

The inside of a rolling bearing is lubricated with oil. The oil may be liquid oil supplied from outside the bearing, or may be the base oil of grease contained inside the bearing.

The inner and outer bearing rings 1 and 2 and the rolling elements 3 are each made of steel.

As shown in FIGS. 3 to 5, the retainer 4 includes an annular portion 7 that is continuous around the entire circumference, and two protrusions in one direction in the axial direction from the annular portion 7 at intervals in the circumferential direction. It has the above claw portion (8).

Between the claw portions 8 facing each other in the circumferential direction, there is a pocket 9 that accommodates the rolling element 3. The pocket 9 is a space where the rolling element 3 can move freely with respect to the retainer 4.

The pocket 9 is open on the radial outer side of the retainer 4, on the radial inner side, and on one side in the axial direction. The rolling element 3 can be accommodated in the pocket 9 through an opening on one axial direction of the pocket 9.

As shown in FIGS. 1 and 2, one of the outer and inner bearing rings 1 and 2 has a circumferential surface 10 that guides the retainer 4. . The circumferential surface 10 is located on the other axial direction of the raceway surface 6 of one of the orbital rings 2 and follows the circumferential direction along the entire circumference.

The circumferential surface 10 in the illustrated example is formed in a cylindrical shape that defines the outer diameter of one of the bearing rings 2.

The retainer 4 has a plurality of pocket inner surfaces 11 that hold the rolling elements 3, and a guide surface 12 guided to the circumferential surface 10.

The guide surface 12 is a surface portion that faces the circumferential surface 10 in the radial direction and has a guide allowance in the radial direction. When the retainer 4 is eccentric with respect to one of the bearing rings 2 by more than the guide clearance, the guide surface 12 and the circumferential surface 10 relatively slide in the circumferential direction. By this sliding, the retainer 4 is guided in the radial direction by one of the orbital rings 2. The guide surface 12 in the illustrated example is formed in a cylindrical shape that defines the inner diameter of the annular portion 7.

The combined roughness of the guide surface 12 and the peripheral surface 10 is 0.7 μm or less. Here, if the synthetic roughness is σ, am. Rq ₁ is the root mean square roughness of the guide surface 12. Rq ₂ is the root mean square roughness of the circumferential surface 10. Here, the root mean square roughness is the value (μm) of the root mean square roughness (Rq) specified in JIS (Japanese Industrial Standard B0601: 2013). The arithmetic mean roughness (Ra) and root mean square roughness (Rq) specified in the JIS have a correlation such that Rq = 1.25Ra.

The lubrication mode in the sliding portion of the guide surface 12 and the peripheral surface 10 can be evaluated based on the value of the oil film parameter (Λ=h/σ). Here, h is the minimum oil film thickness (μm) in the sliding portion of the two surfaces forming the composite roughness (σ). If Λ ≥ 3, the sliding portion is considered to be fluid lubrication in which the two surfaces are completely separated by an oil film, and if Λ < 3, the sliding portion is considered to be boundary lubrication or mixed lubrication that microscopically includes a solid contact portion of the two surfaces. Additionally, since the sliding portion of the circular guide surface 12 and the peripheral surface 10 is regarded as a contact ellipse in the elastic fluid lubrication theory, the minimum oil film thickness h can be calculated based on the theory.

When the combined roughness (σ) of the guide surface 12 and the peripheral surface 10 is set to 0.7 ㎛ or less, the inside of the rolling bearing is lubricated with low-viscosity oil (not shown) recommended for motor shafts, transmissions, differentials, etc. Also, it becomes possible to establish the oil film parameter Λ≥3 starting from the low-speed rotation of the rolling bearing.

Additionally, the roundness of the circumferential surface 10 is 30 μm or less. Here, the roundness is the value of the radius difference between the two concentric circles when an arbitrary circumference passing through the circumferential surface 10 is sandwiched between two concentric geometric circles, and the spacing between the two concentric circles is minimized. In other words, of the entire surface of the circumferential surface 10 that slides with the retainer 4 in the circumferential direction, the radial distance between the central axis and a point located on the outermost radial direction, and the radial distance located on the innermost radial direction The value of the difference in radial distance between one point and the central axis is 30 μm or less. By making the circumferential surface 10 of such a small roundness, it is possible to avoid excessive narrowing locally between the guide surface 12 and the circumferential surface 10, thereby increasing the contact surface pressure between the two surfaces, so that the guide surface 12 The aggressiveness of the circumferential surface 10 made of hard metal is suppressed, and the oil film parameter (Λ) ≥ 3 is established no matter where the guide surface 12 slides at any position on the circumferential surface 10 during low-speed rotation of the rolling bearing. It can lead to sex.

That is, as the sliding portion of the guide surface 12 and the peripheral surface 10 approaches in the circumferential direction, a wedge-shaped gap that gradually narrows in the radial direction is formed. When oil is drawn into the wedge-shaped gap, fluid pressure is generated in the oil due to the wedge action, and when the relative circumferential speed in the circumferential direction between the guide surface 12 and the circumferential surface 10 is above a certain level, the oil film parameter (Λ) ≥3 holds true, and the fluid lubrication state is achieved between the guide surface 12 and the circumferential surface 10.

As a low-viscosity oil that lubricates the inside of the bearing including the retainer 4, for example, an oil with a kinematic viscosity of 50 cst or less at 40°C can be mentioned. Here, the kinematic viscosity is a value measured based on the kinematic viscosity test method specified in JIS (K2283: 2000). By employing low-viscosity oil in this way, the agitation resistance of the oil within the bearing is suppressed.

Oils with a kinematic viscosity of 50 cst or less at 40°C include, for example, oils equivalent to or less than VG46 in the ISO viscosity classification. Preferably, an oil equivalent to VG32 or lower in ISO viscosity classification may be used.

When employing the low-viscosity oil as described above, the composite roughness (σ) of the guide surface 12 and the circumferential surface 10 and the roundness of the circumferential surface 10 are such that the relative peripheral speed between both surfaces is 100 m/s. When , it is desirable to set it to a value where the oil film parameter Λ≥3 is established. Since this peripheral speed is reached in a short period of time after the start of rotation of the rolling bearing, it is possible to quickly transition to a state in which Λ ≥ 3 holds.

The pocket inner surface 11 is a surface portion that defines a pocket margin between the rolling elements 3 and the rolling elements 3, which determines the amount of free movement of the rolling elements 3 with respect to the retainer 4. Therefore, the pocket inner surface 11 can contact the rolling element 3.

When the rolling bearing rotates, the retainer 4 rotates, and the retainer 4 is deformed by the centrifugal force. As the centrifugal force becomes stronger, each claw portion 8 is inclined radially outward, and the annular portion 7 is deformed as if twisted. This deformation reaches the inner surface of the pocket (11), thereby reducing the pocket margin. If the pocket margin becomes negative, the pocket inner surface 11 interferes with the rolling element 3, and they contact abnormally strongly. If the pocket space is increased, the acoustic characteristics deteriorate. In order to bring the acoustic characteristics during high-speed rotation to a practical level, it is desirable to set the pocket margin to 0.5 mm or less.

As shown in FIGS. 3 to 5, the pocket inner surface 11 of the illustrated example includes a pair of cross-section parts 13, 13 formed on opposite sides in the circumferential direction of the claw parts 8, 8 adjacent to each other in the circumferential direction. ) and a pocket bottom surface portion 14 formed on one axial side of the annular portion 7. In order to avoid abnormally strong contact between the pair of cross-section parts (13, 13) surrounding the rolling element (3) when the claw part (8) is tilted by centrifugal force, the cross-section part (13) of each claw part (8) ) has a shape that makes it impossible to fit it to the rolling element 3 in the axial and radial directions. For example, the pair of cross-section parts 13, 13 may be formed into a flat surface shape along the axial direction and the radial direction, respectively, or the pair of cross-section parts 13, 13 may be parallel to each other and form a flat surface shape along the axial direction. You can.

The pocket bottom surface portion 14 has a flat surface shape along the radial and circumferential directions.

The protruding height of the claw portion 8 relative to the annular portion 7 in one axial direction is set to H. The protrusion height H corresponds to the distance between the virtual radial plane in contact with the tip of the claw portion 8 and the virtual radial plane in contact with the bottom of the pocket 9. The tip of the claw portion 8 is a portion of the claw portion 8 located furthest in one axial direction. The bottom of the pocket 9 is the portion located on the other axial direction of the pocket inner surface 11, and in the example shown, it is on the pocket bottom surface portion 14.

The mutual difference in protrusion height H between each claw portion 8 is within 120 μm. Here, the mutual difference in protrusion height H between each claw part 8 means the difference between the maximum protrusion height and the minimum protrusion height among the plurality of claw parts 8.

In order to prevent the rolling element (3) from exceeding the claw portion (8) during high-speed rotation of the rolling bearing, it is set to 0.15d≤H. On the other hand, the smaller the protrusion height H, the less susceptible the claw portion 8 is to the influence of centrifugal force. By setting H ≤ 0.65d, the weight of the claw portion 8 can be reduced and it can be made less susceptible to the influence of centrifugal force.

When H ≤ 0.65d is set and the pocket inner surface (11) is shaped so that it cannot be axially hooked to the rolling element (3), the claw portion (8) and the rolling element (3) are hooked to the retainer (4). ) It is difficult to sufficiently prevent the release of . In order to prevent the retainer 4 from being pulled out, the rolling bearings shown in FIGS. 1 and 2 are positioned in the other axial direction with respect to the retainer 4 so as to regulate movement of the retainer 4 in the other axial direction. It is further provided with a locking member 15 disposed in .

The locking member 15 is an annular sealing member attached to the peripheral groove of the outer bearing ring 1. As the locking member 15, an example using a seal made of an elastic material including a core metal and a seal lip is shown, but a shield containing a metal plate is used, or a locking member dedicated to regulating the retainer is adopted. It is also possible to do so. Additionally, the locking member may be attached to the inner bearing ring.

On the other axial side surface of the annular portion 7, a back surface 16 is formed to face the locking member 15 in the axial direction. A clearance is set between the locking member 15 and the back surface 16. When the retainer 4 is about to fall in the other axial direction with respect to the plurality of rolling elements 3, the back surface 16 of the retainer 4 is received in the axial direction by the locking member 15, and the retainer 4 (4) slides in the circumferential direction with respect to the locking member 15 on the back surface 16.

Each sliding portion of the locking member 15 and other members such as the retainer 4 and the orbital ring 2 can also be transitioned to fluid lubrication. That is, two or more protrusions arranged in the circumferential direction are formed on one of the two surfaces forming each sliding portion, the other surface is made a surface along the circumferential direction, and the protrusions form a wedge between the surfaces of the other side. A mold gap is formed, and oil film formation is promoted through a wedge action when oil between adjacent protrusions in the circumferential direction is drawn between the protrusions and the surface of the other side.

Since the realization of fluid lubrication using the above-described locking member or protrusion row is a technology disclosed in Patent Document 1, etc., detailed illustration description thereof will be omitted.

The combined roughness (σ) of the pocket inner surface 11 of the retainer 4 and the surface of the rolling element 3 held by the pocket inner surface 11 is less than 0.51 μm. The surface of the rolling element 3 is a raceway that is received in the circumferential direction by the inner surface of the pocket 11 for rolling on the inner and outer raceway surfaces 5 and 6 and maintaining the circumferential gap between the rolling elements 3. The surface of the rolling element 3 slides in the rolling direction of the rolling element 3 with respect to the pocket inner surface 11. By setting the combined roughness (σ) of the surface of the pocket inner surface (11) and the rolling element (3) to less than 0.51, when the pocket margin becomes narrow when the claw portion (8) is tilted due to centrifugal force, the pocket inner surface (11) and The increase in sliding resistance between the rolling elements 3 is alleviated, and heat generation in the sliding portion is suppressed.

A cylindrical surface 17 defining the outer diameter of the annular portion 7 is formed on the outer periphery of the annular portion 7. In each claw portion 8, an arcuate surface having the same surface shape as the cylindrical surface 17 is formed. The radial clearance between the cylindrical surface 17 and the inner periphery of the outer raceway 1 is set larger than the above-mentioned guide clearance, and usually the cylindrical face 17 and the raceway 1 are held together by the retainer 4. ) does not contribute to the guidance of

The outer diameter of the retainer 4 is within 600 μm. Here, the variation in the outer diameter of the retainer 4 is the difference between the maximum and minimum values of the actual measured outer diameter obtained over the entire circular surface defining the outer diameter of the retainer 4. In the illustrated example, the cylindrical surface 17 of the annular portion 7 is a circular surface defining the outer diameter of the retainer 4. By reducing the outer diameter drift of the retainer 4 to within 600 μm, the volume distribution around the outer diameter of the retainer 4 is well equalized in the circumferential direction, so that shaking during rotation of the retainer 4 is suppressed. .

The inner diameter of the retainer 4 is within 600 μm. Here, the variation in the inner diameter of the retainer 4 is the difference between the maximum and minimum values of the actual measured inner diameter obtained over the entire circular surface defining the inner diameter of the retainer 4. In the illustrated example, the guide surface 12 of the annular portion 7 is a circular surface defining the inner diameter of the retainer 4. By reducing the inner diameter drift of the retainer 4 to less than 600 μm, the volume distribution around the inner diameter of the retainer 4 is well equalized in the circumferential direction, so that shaking during rotation of the retainer 4 is suppressed. .

The diameter variation of the guide surface 12 of the retainer 4 is within 600 μm. Here, it is the difference between the maximum and minimum values of the actual measured inner diameter obtained over the entire surface of the guide surface 12. By reducing the diameter variation of the guide surface 12 to within 600 μm, the amount of displacement of the retainer 4 in the radial direction due to the diameter variation of the guide surface 12 sliding on the circumferential surface 10 is well suppressed, Vibration during rotation of the retainer 4 is suppressed.

The entire retainer 4 is made of synthetic resin. Here, the concept of synthetic resin includes one type alone, a mixture of two or more types, and one or more types of resin mixed with reinforcing materials (e.g. glass fiber, carbon fiber, etc.) as a base material (so-called fiber reinforced resin). This is included. When using a ball bearing suitable for high-speed rotation, it is preferable to employ fiber-reinforced resin.

As a synthetic resin, engineering plastic is used. Engineering plastics generally refer to plastics that have a heat resistance of 100°C or more and 120°C or less, a strength of 50 MPa or more, and a bending elastic modulus of 2.4 GPa or more.

More specifically, the retainer 4 is formed of polyamide resin, a type of engineering plastic. Examples of polyamide resins include PA, PA6, PA9, PA46, PA66, PA9T+ carbon fiber, and PA46 or 66+ glass fiber.

The entire cage 4 uses a mold (not shown) divided into two parts in the axial direction, injects synthetic resin from gates at one point or multiple points of the mold, and cools and solidifies the injected resin within the mold. It is formed by molding. In order to reduce the surface roughness of the pocket inner surface 11 and the guide surface 12 to reduce the above-mentioned synthetic roughness, the corresponding transfer surface of the mold is, for example, mirror-finished, that is, a surface with a calculated average roughness (Ra) of 0.4 μm or less. It is desirable to do so.

When looking at the surface of the retainer 4, a gate trace, which is a cross section of the synthetic resin sheared when the retainer 4 is released, is formed at a position corresponding to the gate.

As shown in Fig. 3, the gate (gate trace) G is disposed on the surface of the retainer 4 excluding the pocket inner surface 11, guide surface 12, and back surface 16. In the illustrated example, all gates G are arranged on the outer periphery of the retainer 4 including the cylindrical surface 17 of the annular portion 7. The outer circumference of the retainer 4 including the cylindrical surface 17 is not a portion that slides relative to other bearing parts when the rolling bearing rotates. For this reason, even if a burr occurs in the gate trace G on the outer circumference of the retainer 4, the burr in the gate trace G does not rub against other bearing parts when the retainer 4 rotates.

This rolling bearing shown in FIG. 1 is suitable for, for example, supporting a rotating shaft included in a motor or a transmission connected to the motor. An example is shown in Figure 6.

The rotation transmission device shown in FIG. 6 includes a motor 20 for driving the vehicle and a transmission 30 connected to the motor 20. The transmission 30 includes a plurality of rotation shafts 31 to 33, gears 34 to 36 provided on each of these rotation shafts 31 to 33, and a plurality of rolling bearings ( 37, 38). The rotation shaft 21 including the motor shaft of the motor 20 is connected to the rotation shaft 31, and both shafts 21 and 31 rotate as one body. When the vehicle driving motor 20 is the driving source, input is input to the rotating shaft 31 of the transmission 30 from the rotating shaft 21, which is the output shaft of the vehicle driving motor 20, and the transmission 30 has a rotating shaft ( It becomes a gear reducer that reduces the rotation input to 31 and outputs it from the rotation shaft 33. When the vehicle driving motor 20 becomes a regenerative brake, the transmission 30 increases the rotation input to the rotation shaft 33 from the traveling wheel side and rotates the vehicle driving motor 20 from the rotation axis 31 to the rotation axis ( It becomes a gear increaser that outputs to 21).

Each rolling bearing 37 supporting the rotating shafts 21, 31, and 32 is a deep groove ball bearing. The rolling bearing 38 supporting the rotating shaft 33 is a conical roller bearing. Each rolling bearing 37 corresponds to a rolling bearing according to the embodiment shown in Fig. 1 (hereinafter, refer to Figs. 1 to 6 as appropriate).

As described above, this rolling bearing consists of an outer raceway ring 1 having an outer raceway surface 5, an inner raceway ring 2 having an inner raceway surface 6, and an outer raceway surface. It has a plurality of rolling elements (3) disposed between (5) and an inner raceway surface (6), and a retainer (4) for maintaining the circumferential spacing of the plurality of rolling elements (3), and an outer raceway. One of the rings (1) and the inner raceway (2) has a circumferential surface (10) that guides the cage (4), and the cage (4) holds the rolling element (3). It has a plurality of pocket inner surfaces 11 and a guide surface 12 guided on the circumferential surface 10, and in particular, the combined roughness σ of the circumferential surface 10 and the guide surface 12 is 0.7 ㎛ or less, and the circular Since the roundness of the main surface 10 is 30 ㎛ or less, it has an excellent oil film forming ability to the extent that it is possible to increase the oil film parameter Λ in the sliding portion of both sides 10 and 12 to 3 or more starting from low-speed rotation of the rolling bearing. You can get it.

In addition, considering mass production and processability, the composite roughness (σ) of the guide surface 12 and the peripheral surface 10 is preferably 0.4 μm or more. In addition, the roundness of the circumferential surface 10 is preferably 5 μm or more considering mass production and processability.

In addition, in this rolling bearing, the retainer 4 has an annular portion 7 and two or more claw portions 8 protruding in one axial direction from the annular portion 7 at a distance in the circumferential direction. Since the space between the adjacent claw parts 8 and 8 is a pocket 9 that accommodates the rolling element 3, the guide surface 12 and the circumferential surface ( Although the sliding portion of 10) is liable to change narrowly, excellent oil film forming ability is obtained as described above, and thus oil film breakage or premature damage to the sliding portion can be prevented even when rotating at high speed.

In addition, this rolling bearing further includes a locking member 15 disposed on the other axial direction with respect to the retainer 4 so as to regulate movement of the retainer 4 in the other axial direction, and an annular portion ( 7) has a back surface 16 that faces the locking member 15 in the axial direction, the annular portion 7 and each claw portion 8 are integrally formed by injection molding, and the injection molded gate G ) is disposed on the surface of the retainer 4 excluding the guide surface 12 and the back surface 16, thereby shortening the protrusion height H of the claw portion 8, thereby reducing the retainer 4 by centrifugal force. ) can be suppressed from deformation, and the mass production of the retainer 4 is excellent, and even if a burr is formed in the gate mark G, the retainer 4 can be guided to the raceway ring 2 or When the rear surface 16 of the short retainer 4 of the portion 8 is held by the locking member 15 to control its movement, the burrs of the gate trace G may be exposed to the peripheral surface 10 of the raceway ring 2 or Since there is no friction against the locking member 15, it is possible to prevent the rotational torque of the rolling bearing from increasing or becoming a cause of noise and vibration.

In addition, this rolling bearing has a protrusion height (H) between each claw portion (8) when considering the protrusion height (H) of the claw portion (8) in one axial direction with respect to the annular portion (7). Since the mutual difference is within 120 ㎛, even if the claw portion 8 has the maximum protrusion height H, the sliding area of the cross section 13 and the rolling element 3 does not become excessive, and the minimum protrusion height is maintained. Even with the claw portion 8, the rolling element 3 can be sufficiently maintained in the circumferential direction.

In addition, this rolling bearing has a pocket inner surface 11 of the retainer 4 and a composite roughness σ of the surface of the rolling element 3 held on the pocket inner surface 11 of less than 0.51 μm. Heat generation can be suppressed by alleviating the increase in sliding resistance between the inner surface 11 and the surface of the rolling element 3.

In addition, in this rolling bearing, the outer diameter drift and inner diameter drift of the cage are each within 600 μm, so that shaking during rotation of the cage 4 can be suppressed and the vibration value can be further reduced.

In addition, in this rolling bearing, the retainer 4 is formed of polyamide resin, so that while using polyamide resin, which is cheaper than super engineering plastic, as the retainer material, it can withstand use at high-speed rotation. This can be done with (4).

In addition, in this rolling bearing, the kinematic viscosity at 40°C of the oil lubricating the retainer 4 is 50 cst or less, so that the agitation resistance of the oil within the bearing can be suppressed, and further, the torque in the rolling bearing can be suppressed. Energy-saving operation can be promoted by suppressing losses.

The rolling bearing 37 according to the present invention supports the rotation shafts 21, 31, and 32 included in the motor 20 or the transmission 30 connected to the motor 20, thereby maintaining the retainer as an orbital wheel as described above. Since the lubrication of the sliding portion when guiding is excellent, the rolling bearing 37 can be operated at low torque even from low-speed rotation to high-speed rotation, and premature damage inside the bearing can be prevented.

In this embodiment, a deep groove ball bearing is illustrated, but the present invention can also be applied to other bearing types such as angular ball bearings and cylindrical roller bearings.

Additionally, in this embodiment, a prong type retainer is exemplified, but the present invention can also be applied to a basket type retainer.

In addition, in this embodiment, an example is shown in which separation of the cone-shaped retainer and the rolling elements is performed not by a claw but by a locking member, but the present invention also applies to a general tubular retainer in which separation of the conical retainer and the rolling elements is performed by a claw. It is possible to apply it.

In addition, in this embodiment, an example in which the entire retainer is made of synthetic resin is shown, but this invention can also be applied when the retainer is made of other materials. It is preferable from the viewpoint of lubricity and aggressiveness to form the sliding portion with other bearing parts on the surface of the retainer from synthetic resin, but the portion of the retainer outside the sliding portion may be formed from other materials such as metal, for example, reinforcement. For this purpose, it is also possible to construct the inside of the annular part, the annular part, the outer diameter of the claw part, etc., with a metal ring, and insert or adhere the metal ring to the synthetic resin part.

The embodiment disclosed this time should be considered in all respects as an example and not restrictive. Accordingly, the scope of the present invention is indicated by the claims rather than the above description, and is intended to include all changes within the meaning and scope of equivalency to the claims.

1: Outer orbital ring 2: Inner orbital ring (one orbital ring)
3: rolling element 4: retainer
5: Outer orbital plane 6: Inner orbital plane
7: Annular part 8: Claw part
9: Pocket 10: Circumferential surface
11: Pocket inner surface 12: Guide surface
15: Locking member 16: Back side
17: cylindrical surface 20: motor
21, 31, 32: rotation shaft 30: transmission
37: rolling bearing

Claims (9)

An outer raceway ring having an outer raceway surface, an inner raceway ring having an inner raceway surface, a plurality of rolling elements disposed between the outer raceway surface and the inner raceway surface, and the plurality of rolling elements It is provided with a retainer that maintains the circumferential spacing,
One of the outer bearing ring and the inner bearing ring has a circumferential surface that guides the retainer,
The retainer is a rolling bearing having a plurality of pocket inner surfaces for holding the rotating body and a guide surface guided on the circumferential surface,
A rolling bearing, wherein the combined roughness of the circumferential surface and the guide surface is 0.7 ㎛ or less, and the roundness of the circumferential surface is 30 ㎛ or less. According to paragraph 1,
The retainer has an annular portion and two or more claw portions protruding in one axial direction from the annular portion at intervals in the circumferential direction,
A rolling bearing in which a space between the claws facing each other in the circumferential direction is formed as a pocket for accommodating the rolling element. According to paragraph 2,
further comprising a locking member disposed on the other axial direction with respect to the retainer so as to regulate movement of the retainer in the other axial direction;
The annular portion has a back surface that faces the locking member in an axial direction,
A rolling bearing wherein the annular portion and each claw portion are integrally formed by injection molding, and the injection molded gate is disposed on a portion of the surface of the retainer excluding the guide surface and the back surface. According to paragraph 2 or 3,
A rolling bearing wherein, when considering the protruding height of the claw portion in one axial direction with respect to the annular portion, the mutual difference in protruding height between each claw portion is within 120 ㎛. According to any one of claims 1 to 4,
A rolling bearing wherein the combined roughness of the inner surface of the pocket of the retainer and the surface of the rolling element held on the inner surface of the pocket is less than 0.51 μm. According to any one of claims 1 to 5,
A rolling bearing wherein the outer diameter drift and inner diameter drift of the retainer are each within 600 ㎛. According to any one of claims 1 to 6,
A rolling bearing wherein the retainer is formed of polyamide resin. According to any one of claims 1 to 7,
A rolling bearing wherein the kinematic viscosity of the oil lubricating the retainer at 40° C. is 50 cst or less. According to any one of claims 1 to 8,
A rolling bearing that supports a rotating shaft included in a motor or a transmission connected to a motor.

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